1. Field of the Invention
The invention relates to a rolling bearing.
2. Description of Related Art
If an amount of a lubricant (mainly, lubricating oil) supplied to a rolling bearing becomes excessively large, stirring resistance of the lubricant during the rotation of the bearing increases, and thus it becomes difficult to achieve lower torque. Further, if the amount of the supplied lubricant is insufficient, seizure may occur. In order to improve lubricating ability of the rolling bearing, for example, a rolling bearing (an angular contact ball bearing) described in Japanese Utility Model Application Publication No. 5-8045 (JP 5-8045 U) is known. In this rolling bearing, a recess portion, one side of which reaches a raceway shoulder portion, is formed by recessing a portion with which a ball does not come into contact, in a raceway surface of an inner ring or an outer ring, over the entire circumference. (refer to JP 5-8045 U, for example).
In the rolling bearing described in JP 5-8045 U, lubricating oil retained in the recess portion adheres to the ball, and thus, lubrication is performed. However, the lubricating oil retained in the recess portion easily flows out, and thus it is assumed that it becomes difficult to secure the lubricating ability over a long period of time.